I think you wouldn't have to do anything dramatically different other than adding some texturing to the teeth, inner mouth and the outside body. The teeth could keep their original shape, just add detail to give the impression they are huge (with stalactite detail on the teeth, and that detail spreading from the teeth into the gums and inner mouth).

I also agree on improving the Space Slug's movements and adding dust and debris coming out of the cave it is launching itself out of.

Vaderios: kudos on the Ion Cannon shots. Kinda remind me of the V'ger plasma bolts in STAR TREK: THE MOTION PICTURE.

In fact, Vaderios, maybe you could do some shots of the Avenger as it is getting hit and incorporate some of those electrical FX from ST:TMP into the ion blasts (electrical energy arcing around the Avenger superstructure hitting other parts of the ship [like the conning tower], not just cause the flashing lights on the impact zones), as well as show the "lightning" arcing around the Avenger to limited degrees as it drifts downwards and the rebel transport flies beside it.

http://www.youtube.com/watch?v=SwLrEcwtFM4&feature=related
http://www.youtube.com/watch?v=JkywRUAd0_w&feature=related (ion cannon scene at 4:45 - BTW, bad matte shot at 1:04)

You know, watching that clip, I didn't have a problem with the "two fighters against a Star Destroyer?" guy so much as the weak "Yay" uttered by the rebels at 5:07. Granted, it's not going to be like at the end of the Super Bowl, but maybe there could be some tweaking there to make it sound better.